excavate

local tArgs = { ... }
if #tArgs ~= 3 then
        print( "Usage: excavate <length> <wide> <deep>" )
        return
end

-- Mine in a quarry pattern until we hit something we can't dig
local length = tonumber( tArgs[1] )
local wide = tonumber( tArgs[2] )
local deep = tonumber( tArgs[3] )

local depth = 0
local unloaded = 0
local collected = 0

local xPos,zPos = 0,0
local xDir,zDir = 0,1

local goTo -- Filled in further down
local refuel -- Filled in further down

local function unload( _bKeepOneFuelStack )
        print( "Unloading items..." )
        for n=1,16 do
                local nCount = turtle.getItemCount(n)
                if nCount > 0 then
                        turtle.select(n)
                        local bDrop = true
                        if _bKeepOneFuelStack and turtle.refuel(0) then
                                bDrop = false
                                _bKeepOneFuelStack = false
                        end
                        if bDrop then
                                turtle.drop()
                                unloaded = unloaded + nCount
                        end
                end
        end
        collected = 0
        turtle.select(1)
end

local function returnSupplies()
        local x,y,z,xd,zd = xPos,depth,zPos,xDir,zDir
        print( "Returning to surface..." )
        goTo( 0,0,0,0,-1 )

        local fuelNeeded = 2*(x+y+z) + 1
        if not refuel( fuelNeeded ) then
                unload( true )
                print( "Waiting for fuel" )
                while not refuel( fuelNeeded ) do
                        sleep(1)
                end
        else
                unload( true )
        end

        print( "Resuming mining..." )
        goTo( x,y,z,xd,zd )
end

local function collect()
        local bFull = true
        local nTotalItems = 0
        for n=1,16 do
                local nCount = turtle.getItemCount(n)
                if nCount == 0 then
                        bFull = false
                end
                nTotalItems = nTotalItems + nCount
        end

        if nTotalItems > collected then
                collected = nTotalItems
                if math.fmod(collected + unloaded, 50) == 0 then
                        print( "Mined "..(collected + unloaded).." items." )
                end
        end

        if bFull then
                print( "No empty slots left." )
                return false
        end
        return true
end

function refuel( ammount )
        local fuelLevel = turtle.getFuelLevel()
        if fuelLevel == "unlimited" then
                return true
        end

        local needed = ammount or (xPos + zPos + depth + 1)
        if turtle.getFuelLevel() < needed then
                local fueled = false
                for n=1,16 do
                        if turtle.getItemCount(n) > 0 then
                                turtle.select(n)
                                if turtle.refuel(1) then
                                        while turtle.getItemCount(n) > 0 and turtle.getFuelLevel() < needed do
                                                turtle.refuel(1)
                                        end
                                        if turtle.getFuelLevel() >= needed then
                                                turtle.select(1)
                                                return true
                                        end
                                end
                        end
                end
                turtle.select(1)
                return false
        end

        return true
end

local function tryForwards()
        if not refuel() then
                print( "Not enough Fuel" )
                returnSupplies()
        end

        while not turtle.forward() do
                if turtle.detect() then
                        if turtle.dig() then
                                if not collect() then
                                        returnSupplies()
                                end
                        else
                                return false
                        end
                elseif turtle.attack() then
                        if not collect() then
                                returnSupplies()
                        end
                else
                        sleep( 0.5 )
                end
        end

        xPos = xPos + xDir
        zPos = zPos + zDir
        return true
end

local function tryDown()
        if not refuel() then
                print( "Not enough Fuel" )
                returnSupplies()
        end

        while not turtle.down() do
                if turtle.detectDown() then
                        if turtle.digDown() then
                                if not collect() then
                                        returnSupplies()
                                end
                        else
                                return false
                        end
                elseif turtle.attackDown() then
                        if not collect() then
                                returnSupplies()
                        end
                else
                        sleep( 0.5 )
                end
        end

        depth = depth + 1
        if math.fmod( depth, 10 ) == 0 then
                print( "Descended "..depth.." metres." )
        end

        return true
end

local function turnLeft()
        turtle.turnLeft()
        xDir, zDir = -zDir, xDir
end

local function turnRight()
        turtle.turnRight()
        xDir, zDir = zDir, -xDir
end

function goTo( x, y, z, xd, zd )
        while depth > y do
                if turtle.up() then
                        depth = depth - 1
                elseif turtle.digUp() or turtle.attackUp() then
                        collect()
                else
                        sleep( 0.5 )
                end
        end

        if xPos > x then
                while xDir ~= -1 do
                        turnLeft()
                end
                while xPos > x do
                        if turtle.forward() then
                                xPos = xPos - 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        elseif xPos < x then
                while xDir ~= 1 do
                        turnLeft()
                end
                while xPos < x do
                        if turtle.forward() then
                                xPos = xPos + 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        end

        if zPos > z then
                while zDir ~= -1 do
                        turnLeft()
                end
                while zPos > z do
                        if turtle.forward() then
                                zPos = zPos - 1
                                zPos = zPos - 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        elseif zPos < z then
                while zDir ~= 1 do
                        turnLeft()
                end
                while zPos < z do
                        if turtle.forward() then
                                zPos = zPos + 1
                        elseif turtle.dig() or turtle.attack() then
                                collect()
                        else
                                sleep( 0.5 )
                        end
                end
        end

        while depth < y do
                if turtle.down() then
                        depth = depth + 1
                elseif turtle.digDown() or turtle.attackDown() then
                        collect()
                else
                        sleep( 0.5 )
                end
        end

        while zDir ~= zd or xDir ~= xd do
                turnLeft()
        end
end

if not refuel() then
        print( "Out of Fuel" )
        return
end

print( "Excavating..." )

local reseal = false
turtle.select(1)
if turtle.digDown() then
        reseal = true
end

local alternate = 0
local done = false
while not done do
    for k=1, deep do
        for n=1, length do
                for m=1, wide-1 do
                        if not tryForwards() then
                                done = true
                                break
                        end
                end
                if done then
                        break
                end
                if n<length then
                        if math.fmod(n + alternate,2) == 0 then
                                turnLeft()
                                if not tryForwards() then
                                        done = true
                                        break
                                end
                                turnLeft()
                        else
                                turnRight()
                                if not tryForwards() then
                                        done = true
                                        break
                                end
                                turnRight()
                        end
                end
        end
        if done then
                break
        end
    end
        if length > 1 then
                if math.fmod(length,2) == 0 then
                        turnRight()
                else
                        if alternate == 0 then
                                turnLeft()
                        else
                                turnRight()
                        end
                        alternate = 1 - alternate
                end
        end

        if not tryDown() then
                done = true
                break
        end
end

print( "Returning to surface..." )

-- Return to where we started
goTo( 0,0,0,0,-1 )
unload( false )
goTo( 0,0,0,0,1 )

-- Seal the hole
if reseal then
        turtle.placeDown()
end

print( "Mined "..(collected + unloaded).." items total." )